The invention relates to a de-icing system for preventing, by microwave application, the formation of ice and for the de-icing areas of an airplane, which are prone to icing.
Because of meteorological conditions an airplane may become subject to icing during flight. The formation of ice particularly on the aerodynamically supporting, that is the lift generating, structures detrimentally affects the flying capability of an airplane by disturbing the laminar airflow. The airflow may even break off at lower speeds.
Particularly critical areas are the wing slats, which are the extendable sections at the front edges of the wings by which the wings profile can be lengthened for increasing the lift at low flying speeds. Also, the wings are such that the tail section including the rudder and the elevators, the outer wing parts, the engine inlet portion (fairings), the cockpit windows, the PAX doors and the freight doors may be affected.
Because these areas are important for the safety of an airplane, there are already various standard methods for de-icing procedures:
Warm air de-icing: Hot air is taken from the engines and is conducted to the endangered areas by way of a conduit system and valves, PA1 Liquid de-icing: A de-icing liquid is pumped by pumps from a storage tank by way of pipes and valves and distributed by a foraminous steel sheet, PA1 Electric de-icing: The surface areas prone to icing are provided with de-icing mats (electric heating mats), which generate electric resistance heat.
The first and the third of these methods require a relatively large amount of energy during flight, which energy is lost by thermal diffusion into the surrounding metallic wing material. The system of the second case is not available for an unlimited time since the amount of de-icing liquid is limited.
U.S. Pat. No. 5,615,849 discloses a microwave de-icing and anti-icing system for airplane wings, rotors and airfoil wings. Microwave energy is supplied to a hollow conductor in the leading edge of the airplane wing and is converted into thermal energy. A highly absorptive layer on the inner surface of the hollow conductor and a mirror/isolator are used to convert the microwave energy to thermal energy in the most efficient manner. The heat energy is then transferred from the hollow conductor to the surface, the rotor, or the wings, whereby the temperature of those areas is raised sufficiently above the freezing point to cause the ice to break up or to prevent icing in the first place.
Further requirements in the development of airplanes result from the need to handle increasing numbers of passengers, the travelling of longer distances, the reduction of fuel consumption and stricter emission controls. Flight safety, however, is always of greatest importance. As a result, among others, effective de-icing procedures and systems are of prime importance.
It is the object of the present invention to provide a de-icing system for areas of an airplane, which are prone to icing, whereby such areas are maintained free of ice or ice is removed from those areas in a short period in a reliable manner and with minimal energy consumption also when flying through problematic weather zones. New composite materials used in such designs must be suitable for aviation application.